Bulb for mechanical basing



July 3, 1934. D s GUsTlN 1,965,232

BULB FOR MECHANICAL BASING original Filed Dec. 28, 1929 Egff INVENTOR 5.605 7' //V ATTORNEY Patented July 3, 1934 UNITED STATES PATENT OFFICEBULB FOR MECHANICAL BASING Daniel S. Gustin, Bloomfield, N. J., assignorto Westinghouse Lamp Company, a corporation of Pennsylvania 3 Claims.(Cl. 176-32) This invention relates to the manufacture of electricaldevices such as incandescent electric lamps in which a base is securedto a lamp bulb by a mechanical connection between the base and the bulbneck as shown and described yin my I Patent 1,813,572 dated July 7, 1931and is a division of my Patent 1,915,361 dated June 27, 1933 for Methodof sealing-in.

In the manufacture of electrical devices such for example, asincandescent electric lamps, it is the practice to provide the lampIwith a base in the form of a threaded shell or cap having one end opento receive the end or neck portion of a glass bulb. Bases of the abovecharacter have usually been secured to the bulb by means of a quantityof cement which is deposited in the base after which the bulb and baseare disposed in the desired relation and the cement is subjected to abaking operation to harden and firmly secure the bulb and base in fixedrelation.

The above construction has been extensively used but certaindisadvantages attend this mode of manufacture since it is timeconsuming, relatively expensive and involves a heat treating operation.

In my copending application above mentioned, I have provided a structurewhich eliminates the use of cement but at the same time utilizes thestandard type of screw shell or base. The structure set forth in thesaid application includes a split or otherwise resilient collar having acircular outside perimeter and having its central or internal perimeterof non-circular form. The said collar snugly fits the interior surfaceof the base or shell and the non-circular perimeter grips the bulb neck.

It will be appreciated, however, that in order to obtain the propergripping action between the non-circular perimeter of the collar and thebulb neck, that the said neck must be formed to a predetermined shape toconform with the formation of the internal perimeter of the collar sothat when the base is applied over the collar the latter will be firmlypressed into contact with the accommodating formation in the bulb neck.

When the collar and base have been disposed in proper relation the saidbase and collar are secured together by solder or by a brazingoperation. One of the lead wires of the lamp may be disposed between thecollar and the shell while the other lead wire is secured to the usualbottom contact of the shell or base. In the production of incandescentelectric lamps of the mechanically based type above described, it hasbeen found that although satisfactory results may be obtained by formingthe depressions in the bulb neck by ordinary methods, a bulb havin ggreater strength Aat the neck portion is obtamed by performing the bulbshaping operation 1n accordance with the present Vmethod to behereinafter described.

It is an object of the present invention, therefore, to provide a bulbhaving the neck portion shaped and strengthened to receive a retainermember.

Another object of the invention is to provide a bulb having the neckportion shaped to receive a retainer member and having the glass 3frelatively great thickness at the shaped porlon. l

Another object of the invention is to provide a bulb having the neckwall thereof of greater thickness than the remaining wall.

Other objects and advantages of the invention will be more fullyunderstood from the follow- -1 ing description together with theaccompanying drawing in which Fig. 1 is a view of a head showing a bulband mount partly in cross section in position with fires for contractingthe bulb neck about the are tube of the mount to thicken the neckportion of the bulb;

Fig. 2 is a fragmentary view of a portion of the'bulb neck showing thethickened glass after the neck has been shaped;

Fig. 3 is a fragmentary detail cross sectional view showing a jaw toform a depression;

Fig. 4 is an elevational view showing a bulb neck and base securedtogether by a retainer member, the latter being in cross section; and

Fig. 5 is a perspective view of a retainer ring employed for locking abase to the bulb neck.

A bulb embodying the present invention may be made in accordance withthe method set forth in the above mentioned copending application andthe present drawing and description show the important steps of thismethod sufficiently for a clear understanding of the invention claimed.

As illustrated, a bulb 10 having a collet 11 may be suitably supportedwith the neck portion 12 surrounding a flange 13 on a flare tube 14. Theflare tube is, in practice, consolidated with an exhaust tube l5 whichexhaust tube is usually inserted in a holder 16 for the purpose ofdisposing the flare tube in position to be sealed at 17 to.

the bulb neck by sealing fires 18.

After the flare tube and bulb neck are consolidated, the collet issevered. The fusing operation, serving to unite the are tube to thebulb, is termed a sealing-in and leaves the lamp ready for theexhausting operation. 'I'he are tube and exhaust tube are united in whatis termed a press 19' from which extend support wires 20 connected tothe terminals of a filament 21. 'I'his internal structure of the lamp,including-the flare tube, exhaust tube and supported filament, is termeda mount.

In the type of lamp to which the present invention relates, the flaretube is provided with the annular flange 13, as above pointed out, andin the usual practice the operation of sealing the bulb neck to the naretube completes the lamp for the sealing-in operation. In accordance withthe present invention, however, the wall of the bulb neck adjacent tothe flare and extending therefrom is thickened and for this purposeshaping or softening fires 22 are provided. 'I'hese fires, as shown inFig. 2, are directed against the bulb neck at a point above theconsolidation between the bulb and flare tube and serve to soften anappreciable portion of the glass above the flange of the flare tube andcontract the bulb neck at which time the glass accumulates and resultsin a thickened portion 23. As will be noted, the plastic glass tends toiiow downwardly' and provides a thickened portion which extends from theflare tube upwardly and results in what may be termed a reinforced wallor strengthened neck portion on the bulb.

While the glass is still in a plastic condition a plurality of jaws suchas jaw 24, are moved toward the bulb neck to shape the neck portion tosuch a form as to receive a retainer or collar 25, as shown in Fig. 4.The collar, as shown in Fig. 5, is in the form of a split ring having aninterior perimeter comprising three straight surfaces 26, 27 and 28. Inthe present construction three jaws 24 may be provided of substantiallythe same shape as one of the straight edges of the collar 25 so thatwhen the jaws have pressed the neck of the bulb to the proper depth, thestraight edges 26, 27 and 28 of the retainer member will be accommodatedby the depressions formed and the said edges will seat in thedepressions so that the retainer member will snugly fit the shapedportion of the bulb neck and be ready to receive a base 29 which litsthe collar and may be suitably secured thereto.

It will be noted that a bulb made in accordance with the presentinvention is provided with the neck portion thickened substantiallythroughout the portion between the seal and the shoulder 30 at the endof the cylindrical portion of the neck. Usually a screw base whensecured to the bulb is so positioned that the upper edge of the base isseated on or close to the shoulder. The cylindrical portion of thebulbvis relatively strong since it has not been rendered plastic andworked as has the lower portion. Therefore, by thickening the wallbetween the seal and the shoulder an extremely strong wall is provided.

During the operation of shaping the bulb neck by means of jaws 24, airunder pressure may be directed through the exhaust tube whichcommunicates with the interior of the bulb so that the softened glass isforced firmly against the shaping jaws. In practice it has been foundpreferable to sever the collet by suitable cutoff fire after the formingjaws 24 have pressed and shaped the bulb neck. Suitable annealing firesmay be employed to anneal the closed portion of the neck before thesevering-off operation is performed. It has also been found desirable,during the severing operation, to ,direct one or more jets of airagainst the shaped portion of the bulb neck to cool the same.

After the collet has been removed an operation termed a pull-down isperformed. This operation consists in moving the vmount relative to thebulb while the glass portion of the seal is still plastic. In lampmaking machines lthe pull-down operation is accomplished by a downwardmovement of the holder or chuck which secures the exhaust tube. Theplastic material at the seal is thus worked and internal stresses areremoved. Means for causing the pull-down are not shown since thisfeature is well known in the lamp art. It is pointed out, however, thatalthough the present bulb distinguishes from others in having thereinforced or thickened neck, it still may embody the pulldown featureto remove internal stresses, thus giving the desired strength and at thesame time retaining the necessary practical form in which detrimentalstresses are avoided.

In addition to the pull-down, however, it has been found desirable, whenthe bulb is ready to be exhausted, to direct an annealing fireI againstthe union between the bulb and the are tube and further to removeinternal stresses.

In the manufacture of incandescent electric lamps the desirability ofavoiding the use of a basing cement and mechanically attaching a base toa bulb has long been considered desirable. The `.manufacture ofincandescent lamps, wherein it is necessary to seal or consolidate twoglass parts, made the use of a mechanical base extrernely difficult.

It will be appreciated that when a base is to be held to a bulb neckcertain stresses are iinparted upon the neck and since the glass of thisportion of the bulb has necessarily undergone changes, due to working,it is less resistant to breakage than would be the case with a glassporition as originally received from a blowing operaion.

The present invention provides a. bulb with a neck portion which is notonly shaped but strengthened to such extent that it provides a ruggedsupport for the means which hold the base in position.

The bulb, as provided by the present invention, is not one wherein theneck is provided with a mass of glass but it is so constructed that theneck portion is strengthened by a distributed thickened glass portion.The wall, as clearly shown, is of increased thickness for an appreciabledistance extending from the flange of the flare tube. This gives thewall of the neck strength not only in one direction, as in the case of amass of glass around the lower portion, but the necessary strength inall directions to provide an effective and practical bulb' which may beprovided with a base mechanically secured thereto in such manner as tomeet commercial requirements.

Although a preferred embodiment of the invention is shown and describedherein it is to be understood that modifications may be made thereinwithout departing from the spirit and scope of the invention as setforth in the appended claims.

What is claimed is:

1. An incandescent electric lamp comprising a bulb for receiving a baseretainer member, a flare tube having the flange thereof integral withthe wall about which the retainer member is disposed. bulb having acylindrical neck portion and an end 2. An incandescent electric lampcomprising a. portion, a flare tube having a flange integral with bulbfor receiving a base retainer member, a said end portion, the wall ofsaid end portion iiare tube having the flange thereof integral withextending between said flange and said cylindrithe bulb neck, said bulbneck having the material cal portion being of relatively great thicknessas 8O of the wall thereof thickened at a point adjacent compared to thewall of said cylindrical portion to said iiange to strengthen theportion of the and of gradually decreasing thickness toward the wallabout which the retainer member is disspherical wall of the bulb, saidthickened wall posed, said thickened wall having depressions to havingdepressions shaped to receive a base rereceive portions of a retainermember. tainer member. 85 3. An incandescent electric lamp comprising aDANIEL S. GUSTIN.

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